The performance of polarized multiple-input-multiple-output (MIMO) systems can be significantly influenced by the antenna's cross-polar discrimination (AXPD) depending on the channel characteristics in communication scenarios utilizing radiating cables. Vertically polarized radiating cables, commonly used in these settings, often suffer from low AXPD due to inherent design constraints that compromise polarization purity, thereby limiting the system's ability to effectively manage multiple data streams. This study proposes a novel approach to enhance the AXPD of vertically polarized radiating cables for MIMO applications. The proposed design utilizes a recticoax cross-section as the feeder structure, optimized through the two-dimensional finite difference (2D-FD) method, which allows for precise modeling and improvement of the electromagnetic properties of the cable. The research specifically examines a scaled version of the enhanced cable design, tailored for operation within the 1700 to 4200 MHz frequency range— a spectrum critical for modern wireless communications. Simulation results indicate a significant improvement in AXPD, suggesting that the proposed design could considerably enhance the performance of MIMO systems using vertically polarized radiating cables. This advancement addresses key limitations of current designs, offering new opportunities for improving polarization performance and, consequently, the overall efficiency of MIMO communication systems in complex environments.